Falls are an important and potentially costly cause of injuries in older adults. Despite being heavily promoted, traditional exercise programs have thus far been inconsistently successful in reducing falls in older adults. Many of these exercise programs focus on improving maintenance stance as the body moves but in a relatively slow manner, i.e. slow dynamic balance. Perhaps an exercise program that is also directed toward dynamic balance but involving relatively fast movements might improve the ability to respond quickly to an impending fall (i.e. improving fall protective responses) and therefore show a stronger effect in reducing falls. Among these fall protective responses, the ability to make rapid stepping responses is often required to maintain standing balance. We propose to train older adults in a 3-month balance training program, combining a focus on improving both the ability to maintain stance and the ability to improve rapid stepping response. We will randomize older adults with mild-moderate balance deficits to one of other two groups: 1) the Combined Balance Training program or 2) T'ai Chi. The 3-month Combined Training and T'ai Chi will be followed by a 12 month home- based maintenance program with weekly group "refresher" sessions. Both groups will be under surveillance, via postcard responses and telephone calls, for the primary outcome, occurrence of falls and fall-related injuries. Intermediate outcomes at baseline, 3 months and 15 months will include measures of maintaining stance and rapid stepping. Secondary analyses will explore the relationships between apparent underlying mechanisms such as changes in rapid strength development and self efficacy as explanations for changes in maintenance of stance, rapid stepping, and the occurrence of falls. Thus, in addition to improving the balance and rapid stepping ability of participating subjects, a number of questions may be explored regarding postural control and the ability to avoid falls in an at-risk older adult population.